Action Points

Obese young adults whose weight decreased to a non-obese body-mass index (BMI) before reaching middle age dramatically reduced their risk for diabetes, according to a retrospective cohort study.

Realize that that kind of weight loss was difficult to achieve, and only 1.1% of the more than 21,000 study participants managed to do it, while 14.6% gained weight and became obese by middle age.

Obese adults who shed pounds and dropped down to a non-obese body-mass index (BMI) before hitting middle age dramatically reduced their risk for diabetes, according to a retrospective cohort study.

These individuals lowered their risk by nearly 70% (hazard ratio 0.33; 95% CI 0.14-0.76) compared with those who were obese as young adults and stayed that way in middle age, researchers led by Andrew Stokes, PhD, of the Boston University School of Public Health, reported in Diabetes Care.

Not surprisingly, that kind of weight loss was difficult to achieve, and only 1.1% of the more than 21,000 study participants managed to do it. Gaining weight and becoming obese by middle age was much more common (14.6%). In addition, approximately 5% of participants were obese both as young and middle-aged adults, the researchers said.

Even individuals with a normal BMI as young adults but who then became obese by middle age had a lower diabetes risk compared with those who were obese both as younger and older adults (HR 0.70; 95% CI 0.57-0.87), the study found.

"A large percentage of the observed diabetes cases could have been averted with effective intervention and prevention efforts in young adulthood," Stokes and colleagues said. They estimated that if all of the obese younger adults had dropped to a non-obese BMI (<30) before middle age, 9.1% of incident diabetes cases could have been prevented. If all adults in the study had maintained a normal weight throughout the study period, 64% of cases (95% CI 59%-68%) could have been prevented.

"This study demonstrates there is a window of opportunity between early adulthood and middle age to largely prevent one of the most serious consequences of obesity," study co-author Robin Scamuffa, MS, director of clinical affairs at Ethicon in Cincinnati, said in a news release from the company, which helped support the research. "Obesity is a preventable cause of diabetes, and higher awareness of the long-term risks of obesity is needed, particularly among younger people."

"Younger Americans are at a high risk for developing diabetes later in life if they are unable to prevent or overcome obesity," added Stokes, also in the news release. "The findings from this study underscore the importance of population-level approaches to the prevention and treatment of obesity and diabetes across the life course of individuals."

The researchers analyzed data on 21,554 adults from the National Health and Nutrition Examination Survey (NHANES) in 1988-1994 and 1999-2014. The mean age at baseline was 44, and half the participants were women. The majority (79%) were white, 9% were black, 8.5% were Hispanic, and 3.5% were other races and ethnicities.

Participants underwent a physical exam and completed a survey, and were asked to recall their weight at age 25 and to self-report a diagnosis of diabetes. The mean BMI at age 25 was 23.6, and at the end of follow-up, was 27.8. The incidence of diabetes ranged from 5% for those who were not obese at any time to more than 20% for those who were obese both as young and middle-aged adults.

Participants were categorized into four weight-change groups:

those who were never obese

those who lost weight and went from obese to non-obese

those who gained weight and became obese

those who were always obese.

The researchers used Cox proportional hazard models to examine the relationship between weight change and diabetes incidence over 10 years of follow-up.

One limitation of the study, the authors noted, was its reliance on self-reported weight: "Although prior studies have shown self-reported weight is a strongly correlated predictor of actual weight, our use of historic self-report likely introduced error." In addition, the analysis did not adjust for diet or physical activity because recall data on these variables were not collected -- "The results may thus partly reflect the effects of physical activity and dietary factors over the life course."

Nevertheless, Stokes et al said, "the findings from a national sample underscore the importance of developing policies and programs that reduce the prevalence of obesity."

The study was funded by the National Institutes of Health and Johnson & Johnson.

Stokes reported research funding from Johnson & Johnson; Scamuffa and two other co-authors are employees of Ethicon, a Johnson & Johnson company, and two other co-authors are employees of Johnson & Johnson.

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